Zirconium phosphate-based inorganic ion exchangers are utilized in various applications by virtue of their features.
The zirconium phosphate-based inorganic ion exchangers include amorphous ones, and crystalline ones having a two-dimensional layer structure or three-dimensional network structure. Above all, Zr2(HPO4)2.nH2O, which is a layered zirconium phosphate having a two-dimensional layer structure, is excellent in ion exchange performance, heat resistance, chemical resistance, radiation resistance and the like, and is applied to a trapping agent for impurity ions in electronic materials, immobilization of radioactive waste, a solid electrolyte, a gas adsorbing/separating agent, a rust preventive, a catalyst, an intercalation carrier, a raw material for antibacterials and the like.
Hitherto, various types of layered phosphates have been known and various types of synthesis methods thereof have also been known. For example, there are Zr(HPO4)2.H2O, Zr(HPO4)2.2H2O, Ti(HPO4).H2O, Ti(HPO4)2.2H2O, Hf(HPO4)2.H2O, and Sn(HPO4)2.2H2O (for example, see Patent Document 1), and M(IV) (HPO4)x.nH2O (where M(IV) is a tetravalent metal) (for example, see Patent Document 2).
Above all, layered zirconium phosphates are easy to synthesize and excellent in performance and the like, and thus various manufacturing methods thereof have been proposed. For example, there are Patent Document 3, Patent Document 4 and Patent Document 5. Synthesis methods for layered zirconium phosphates include a hydrothermal method in which raw materials are mixed in water or in a state of containing water, and thereafter pressurized and heated to effect the synthesis, and a wet method in which raw materials are mixed in water, and thereafter heated at atmospheric pressure to effect the synthesis.
LSIs, ICs, hybrid ICs, transistors, diodes, thyristors and hybrid components thereof are sealed with an epoxy resin, for example. Epoxy resins are also used as adhesives for flexible printed wiring boards which have recently been demanded increasingly. Such sealing materials for electronic components are required to suppress failure caused by ionic impurities originating from raw materials or moisture invading from outside, and to have various characteristics including flame retardancy, high adhesiveness, crack resistance and electric properties including high volume resistivity.
Epoxy resins that are frequently used as electronic component sealing materials are composed of an epoxy compound as the main component, and additionally an epoxy compound curing agent, a curing accelerator, an inorganic filler, a flame retardant, a pigment, a silane coupling agent and the like.
Further, recent higher integration of semiconductors has brought about earlier generation of corrosion of aluminum due to reduction of the aluminum interconnect width on IC chips. This corrosion is promoted mainly by moisture invading an epoxy resin used as a sealing material. Since more heat is generated upon use due to the reduction of the interconnect width, a large amount of a flame retardant such as antimony oxide, a brominated epoxy resin and an inorganic hydroxide is added to the epoxy resin, thereby further promoting corrosion of interconnects made of aluminum or the like.
In flexible printed wiring boards, migration of copper interconnects is generated earlier for a similar reason.
A composition is known which comprises an epoxy resin used for printed wiring boards, blended with an inorganic ion exchanger such as a cation exchanger, an anion exchanger or an amphoteric ion exchanger (for example, see Patent Document 6).
A printed board is known which is made from aramid fibers impregnated with an epoxy or polyphenylene oxide resin and an ion trapping agent. The ion trapping agent is exemplified by an ion exchange resin and an inorganic ion exchanger; and as the inorganic ion exchanger, an antimony-bismuth-based one and a zirconium-based one are described (for example, see Patent Document 7).
An insulating varnish containing an ion trapping agent is known; and a multilayer printed wiring board is fabricated using the insulating varnish. The ion trapping agent is exemplified by activated carbon, zeolite, silica gel, activated alumina, activated clay, hydrated antimony pentoxide, zirconium phosphate and hydrotalcite (for example, see Patent Document 8).
An adhesive film for multilayer wiring boards is known in which an inorganic ion adsorbent is blended. The inorganic ion adsorbent is exemplified by activated carbon, zeolite, silica gel, activated alumina, activated clay, hydrated antimony pentoxide, zirconium phosphate and hydrotalcite (for example, see Patent Document 9).
An epoxy resin adhesive containing an ion trapping agent is known. The ion trapping agent is exemplified by an anion exchanger and a cation exchanger (for example, see Patent Document 10).
A conductive epoxy resin paste is known which contains an ion trapping agent, silver powder and the like. The ion trapping agent is exemplified by hydrated bismuth nitrate, magnesium aluminum hydrotalcite and antimony oxide (for example, see Patent Document 11).    Patent Document 1: Japanese Patent Laid-Open No. 03-150214    Patent Document 2: Japanese Patent Laid-Open No. 59-102808    Patent Document 3: Japanese Patent Laid-Open No. 60-103008    Patent Document 4: Japanese Patent Laid-Open No. 62-226807    Patent Document 5: Japanese Patent Laid-Open No. 61-270204    Patent Document 6: Japanese Patent Laid-Open No. 05-140419    Patent Document 7: Japanese Patent Laid-Open No. 09-314758    Patent Document 8: Japanese Patent Laid-Open No. 10-287830    Patent Document 9: Japanese Patent Laid-Open No. 10-330696    Patent Document 10: Japanese Patent Laid-Open No. 10-13011    Patent Document 11: Japanese Patent Laid-Open No. 10-7763